1. Field of the Invention
The present invention relates to a method for manufacturing an absorber using a resin fiber, and more particularly to an absorber which holds ink to supply ink to an ink jet head.
2. Description of the Related Art
Conventionally, an absorber for holding ink has been used in an ink tank which supplies ink to an ink jet head. In a state other than recording, the absorber is required to hold the ink to prevent the ink from leaking to the outside. During the recording, the absorber is required to supply the ink stably to the ink jet head. It is proposed that a foam member such as urethane foam or a fiber member such as polyolefin are used as the absorber in general, so that the ink is held by a capillary force generated therein as a negative pressure generation source.
Regarding a method for manufacturing a resin fiber absorber, the following two methods have been proposed. The first is a method for taking out a fiber material by weight equal to one absorber (hereinafter, “individuation”), and then processing the fiber material into a shape of an absorber (hereinafter, “forming”).
Japanese Patent Application Laid-Open No. 7-47688 discusses a manufacturing method for forming an absorber after such individuation. While an individuation method is not described in detail, as a forming method, heating and melting of a surface of an ink absorber member configured with a resin fiber by a heater is discussed. Specifically, a fiber absorber is inserted into a mold having one surface opened, and heated by the heater in a state where constant pressure is applied from the opening to the absorber. The fiber of the absorber surface in contact with the heater is melted, and then cooled to harden. The fiber of the heated and melted place is fused. By repeating this process six times, an absorber having a hexahedral shape is acquired.
The second is a method for performing individuation after forming. Japanese Patent Application Laid-Open No. 7-323566 discusses a forming method that forms a resin fiber raw material into a thin web sheet, needle punches the sheet to mechanically entangle fibers, and then heats entire fibers to form the sheet. Then individuation into a shape of an absorber is performed by a punch die.
The ink absorber uses, as a unit for generating negative pressure to hold the ink, a capillary force generated by forming a fine void area therein. Thus, how the fine void area in the absorber can be controlled is important.
When only the absorber surface is heated and melted as discussed in Japanese Patent Application Laid-Open No. 7-47688, it may be difficult to hold the shape by suppressing a repulsive force of the absorber, which is becoming larger in recent years, for the ink tank. In other words, when the absorber is taken out of the mold for heating and melting, a shape and a size of the absorber may not be maintained due to a large fiber repulsive force. When the absorber is inserted into the ink tank, a fiber density of a portion pressed to a tank wall increases, and hence an initially designed capillary force may not be acquired.
To suppress such a fiber repulsive force, a configuration can be employed in which processing is performed not only for the absorber surface but also into the absorber. To suppress the repulsive force, as discussed in Japanese Patent Application Laid-Open No. 7-323566, setting a thermal curing step to harden the entire fiber absorber after needle-punching generally used in the textile industry is effective. However, individuation into the shape of the absorber by the punch die after the forming step, as discussed in Japanese Patent Application Laid-Open NO. 7-323566, leads to generation of waste materials depending on the size of the absorber, causing a difficulty of increasing use efficiency of raw materials.